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APPENDIX A: TECHNICAL SPECIFICATIONS
875DP/500DP/500HV DUAL PULSE
RESISTANCE WELDING
POWER SUPPLIES
A-10
990-290
Footswitch Type
These power supplies require the use of a 1-level or 2-level footswitch in order to control an air actuated
weld head. They will automatically detect whether a Unitek Peco 1-level or 2-level footswitch is connected
to the FOOTSWITCH connector located on the rear panel.
The power supply assumes that a 1-level footswitch is used if the input to the 2nd level is continuously
closed. The power supply determines whether it is connected to a 1-level or 2-level footswitch whenever it
enters the RUN state. The options menu can be used to override the automatic selection feature. You can
simulate a 1-level footswitch by connecting Pins 3 and 4 on the Footswitch connector.
FOOTSWITCH Connector
The FOOTSWITCH connector is a 4-pin Amphenol 91-PC4F (Unitek Peco PN 550-006) that mates
with an Amphenol 91-MC4M (Unitek Peco PN 520-009). Connect Pin 3 to Pin 4 on a user supplied 1-
level footswitch. This connector is wired as follows:
Pin
Description
1 Chassis
Ground
2
Footswitch Level 1 or Single Level Footswitch
3 Footswitch
Level
2
4 Common
Footswitch Weld Abort Feature
The footswitch weld abort feature is controlled from the options menu.
Footswitch Weld Abort On
With FOOTSWITCH WELD ABORT ON selected, the welding sequence is initiated by the closure of
the initiation switch, and continues to its conclusion as long as the initiation switch remains closed. If
the initiation switch or the force firing switch open during the welding sequence, the sequence will
terminate. FOOTSWITCH WELD ABORT ON is preferred since it allows the operator to abort the
welding sequence by releasing the footswitch, or footpedal in the case of a manual head.